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3304 cat fuel pressure

Started by Caseybow123, November 11, 2020, 04:48:44 PM

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Caseybow123

Hey everyone.  Another issue with my 518 cat skidder. Had a problem with some bad fuel awhile back, now having a horrible time trying to start this thing. Changed fuel filters out 3 different times hoping that I eliminated the problem. It will crank over forever but will not fire and won't build fuel pressure. Does have any resistance on the manual primer pump either. If I pour the starting fluid to it, it finally starts and fuel pressure then registers where it's supposed to be. Runs great after its started. Shut it off for 5 or 6 hours and same issues. Ideas???

Loggergus

Sounds like you are getting air in the fuel line...make sure that there's no pinholes in the fuel lines on the motor... might not be big enough to leak fuel but let's the fuel drain back while sitting...

Caseybow123

I had wondered that as well, but it seems like a big coincidence that this started after I got a bad batch of fuel. Just wondering if there is some type of valve maybe stuck open allowing fuel to drain back.

mike_belben

I only know bosch systems well and standadynes somewhat, not cat.  But it very well may have a valve to keep the low pressure galley charged with fuel.  


On a bosch this would be called the overflow valve or ofv and its just a ball bearing and a spring located in the banjo bolt on the outlet side of the line back to tank.  When you hand prime a bosch pumped truck or tractor youll actually hear the fuel spurting back to tank out that valve line which tells you the galley is charged up and ready to fire.  


Keep close tabs on your oil level ..make sure it isnt rising because bad seals in the pump will probably drain back to the crankcase if its lubed by engine oil. 
Praise The Lord

Caseybow123

Thanks for your expertise Mike, I will check it out and see. This engine is direct injection if this helps with diagnosis. Is there always some fuel pressure or after sitting does it release only to build up again when the engine cranks? The longer it sits, the harder it is to get pressure and start.

mike_belben

Again im flying blind on cat pumps but that sounds like a drainback issue to me if its not leaking any fuel externally.  

If it had a continual inlet air issue on the fuel suction side of whatever lift pump they use, you'd hear it farting in the exhaust note to some degree or other. Kinda like a burbly sound.. Like a gasser with a bad plug wire.  Purging once then running great is a loss of prime in the low pressure supply, then a sufficient reprime.
Praise The Lord

BargeMonkey

What Mike said. I recently went thru a similar problem on my Timbco, started at the injector lines and worked backwards. 

Skeans1

On our 3204 in a track skidder they have some in line screen filters that can plug up, memory says one is on the pump and the other is in a hard line union fitting.

mike_belben

Definitely should find and clean your rock catchers and put some paint on the locatios while yer in there.. But a clogged rock catcher will usually start and idle then quit under power.  I think its gonna be a check valve with junk in the seat or a broke spring behind it.  Or maybe an o-ring issue if they are poppet style.
Praise The Lord

moodnacreek

Does it use a lift pump? A weak one will do this. My C cummings got like this, draining back and starting hard and the hand prime didn't sound right. Drained the filters and filled them with sea foam and that trick fixed it.

mike_belben

In 6BT cummins the cam shoves the lift pump pushrod into a spring and while checkvalving mechanically that spring squishes the fuel so its like a mechanical syringe.. Thats why a 12v will have pulsing fuel lines.  


2x i have had the spring be snapped and sitting coiled inside itself.  Still ran but weak.  

Lift pump is certainly a path back to tank and among the usual suspects here. 
Praise The Lord

Caseybow123

Mike,
When you say "lift pump", are you referring to the fuel transfer pump? I was suspecting maybe there is a leak with it as it takes forever to build fuel pressure while cranking but is smoking terribly. Also when it does fire up, it takes about 10 seconds or so for all injectors to fire correctly. 

mike_belben

Yes sir, lift pump and transfer pump are interchangeable terms for any type of pump that brings fuel from the tank to the high pressure injection pump.  


Looks like oring may be a failure mode for your cat.   In a perfect world, once primed your injection pump should wake up with the same supply pressure it went to bed with. Should be pretty easy to check with a tee and a gauge. 

https://nyheavytractor.com/products/3304-3306-fuel-transfer-pump-kit-replacement-caterpillar-1w1669-8n2641-1w-1669?variant=31568400613428&currency=USD&utm_medium=product_sync&utm_source=google&utm_content=sag_organic&utm_campaign=sag_organic&utm_campaign=gs-2019-12-12&utm_source=google&utm_medium=smart_campaign
Praise The Lord

Caseybow123

Thanks again Mike. I am betting on something within the transfer pump as well. For the price of a kit, it is well worth trying anyway. I don't have to put a gauge on to see the pressure loss. The qauge on the machine while running is in the green and after 4 hours of shut down it is in the red.
Thanks for your help. I will post the results once a get a kit.

Mountain_d

Make sure the return line is not leaking also. You would not think a return matters, but it does. I had a similar problem on my 4B Cummins. I removed the return line to change the filter. When I re-attached the return line, I forgot to tighten the clamp. If it sat overnight, would fire up, die instantly, then need to crank and crank and crank. Once started, if I shut if off for an hour or so, it would fire up no problem. 
Mountain. 
1978 TJ 230E 3.9L Cummins 4B, Husky 372XP, Husky 61, Husky 266XP, JRed 625, Husky 265RX clearing saw,  Woodmizer LT40HD 1995, Kubota 4950DT (53hp 4WD), Wallenstein V90 Skidding Winch, John Deere 610 backhoe, 1995 Volvo White GMC WCA42T SA Dump Truck, 2004 Ford F-250SD 4WD, , Central Boiler OW

kiko

If it has one of those hand primer pumps that you unscrew and the pump leaks fuel out when you pump then that is an air leak. Below that pump is are some check valve that can make the fuel leak off. On my 525b every time it has set for more than a day it requires pumping. Granted the 3126 has a different fuel system but I imagine that primer pump is the same.

Caseybow123

Thanks Kiko 
I have noticed that the hand primer pump is not working properly too.  It does pump fuel to the filter,  but when you stop pumping you can here air escaping. I will be changing that as well seeing that the machine was born in 1975.

mike_belben

Hand primers are built sorta like bottle jack pumps.. Orings will leak over time.  Good chance that is a big part of your issue. 
Praise The Lord

csmall61

On a Cat 963 track loader with the 3304 engine, the fuel priming and primary filter has a check valve on the inside of the priming pump body outlet.  You have to remove the fuel priming and primary filter assembly and disassemble it to get access to remove the check valve.  This is more than likely the problem.  The Cat track loader check valve part number is 7E5346, yours will of course be different.

kiko


Caseybow123

My primer pump is different, probably due to engine arrangement however it serves the same purpose. 
I know when you see brass filings when trying to prime the system,  "Time to replace".


 

 

Caseybow123

Replaced hand primer pump yesterday as I knew it was not operating properly. Hard starting issues still remain.  The only plus side is that I can now prime the fuel system to help with starting,  but has not fixed the problem. What next, transfer pump??

barbender

How is your fuel supply coming to the pump? Does it gravity feed from the tank? Being you had bad fuel, I would suspect a supply line restriction. That wouldn't cause it to lose pressure while sitting, but I'd still start there and make sure the supply pump is getting plenty of fuel to begin with.
Too many irons in the fire

Caseybow123

I blew out all lines so I know that there is no fuel restriction.  Also, when I do get the skidder started, it runs fine with no hesitations or loss of power.

mike_belben

Praise The Lord

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